1. The Field of the Invention
The present invention relates to a magnetic data eraser that is configured to erase magnetic data stored in a magnetic recording medium such as a hard disk drive (HDD).
2. Description of Prior Art
At the present time, when a magnetic recording medium (hereinafter, exemplified by a hard disk drive) is to be discarded after its use has terminated in an office or by an individual person, in order to conceal the magnetic data stored in the hard disk drive from unrelated persons, the magnetic data contained in said hard disk drive (HDD) is often erased by formatting the HDD using commands from the operating system of the computer in which the hard disk drive is installed.
However, when the above mentioned method is used, the only part of the HDD that is erased is the data management-related portion which is used to manage the handling of magnetic information on the hard disk. The actual magnetic data information itself may remain on the hard disk and may be recoverable. For this reason, other methods have been developed such as, for example, a method for erasing information stored in the magnetic disk drive by applying magnetic force generated by an electromagnet to the magnetic disk drive.
Japanese Laid-Open Patent Application listed in 0005 below discloses an invention related to a data eraser that performs the data erasing process with a simple operation in order to prevent a data leak of magnetic data stored in the magnetic recording medium to be discarded, and in particular discloses an invention relating to a data eraser that performs the data erasing process by applying a horizontal magnetic field from a magnet to the magnetic recording medium.
Japanese Laid-Open Patent Application 2007-66439
However, currently, the perpendicular magnetic recording method has become widely adopted. In perpendicular magnetic recording, the magnetic write field is applied to the magnetic disk drive in a direction perpendicular to the disk's surface in order to store data in the magnetic recording medium. This perpendicular magnetic recording method is considered to be more effective than the in-plane magnetic recording method (or linear magnetic recording method) which was the conventional recording method, including the method disclosed in Japanese Laid-Open Patent Application 2007-66439, because the perpendicular magnetic recording method can provide better performance than the in-plane magnetic recording method, such as providing a higher data recording density.
Hence, when it has been desired to erase data stored in a magnetic disk drive in situations where it is not known whether the recording direction is perpendicular or linear, it has been necessary to operate a data eraser to apply a magnetic field in the direction horizontal to the magnetic disk drive and then further to apply a magnetic field in the direction perpendicular to the magnetic disk drive, or apply a two to three times stronger magnetic field in order to avoid insufficient erasure because of improper direction of the magnetic flux angle.
This has required a longer time and more complex operations to perform the data erasing process and/or more power required for erasing data stored in a magnetic recording medium including media that have been recorded in the perpendicular direction, than in the case of using a conventional data eraser (that is, an eraser for linear recorded media only).
Meanwhile, a method has been proposed for erasing data stored in a magnetic recording medium by applying a magnetic field, wherein the magnetic recording medium such as a magnetic disk device is mounted in a data easer so that the magnetic recording medium is inclined to magnetic flux generated by the data eraser. However, in this method, no suitable value has been proposed for the angle at which the magnetic recording medium is inclined.